This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2002-003122, filed Jan. 10, 2002, the entire contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a liquid crystal display apparatus having display panels on both upper and lower surfaces.
2. Description of the Related Art
For example, as shown in FIG. 12, there is some cell phone designed such that a display portion housing 2 is pivotally attached to an operation key portion housing 1 through a shaft 3. In this case, a key operation portion 4 is formed in the area enclosed with chain lines on the opposite surface of the operation key portion housing 1 to the display portion housing 2. A liquid crystal display apparatus 5 is housed in almost the central portion inside the display portion housing 2.
The display surface of a main liquid crystal display panel 6 is exposed on the opposite surface side of the liquid crystal display apparatus to the operation key portion housing 1. As shown in FIG. 13, when the display portion housing 2 is closed with respect to the operation key portion housing 1, the display surface of a sub liquid crystal display panel 7 smaller in area than the main liquid crystal display panel 6 is exposed on the opposite side to the opposite side of the display portion housing 2 to the operation key portion housing 1.
As described above, there is some cell phone having the liquid crystal display panels 6 and 7 mounted on the two surfaces of the display portion housing 2 pivotally attached to the operation key portion housing 1 through the shaft 3. The sub liquid crystal display panel 7 is used to display the date/time, received contents, the telephone number of the sender, or the like while the display portion housing 2 is closed with respect to the operation key portion housing 1.
FIG. 14 is a sectional view of part of a conventional liquid crystal display apparatus incorporated in such a cell phone. In this liquid crystal display apparatus, the main liquid crystal display panel 6 and sub liquid crystal display panel 7 are placed to oppose each other at a predetermined distance, a main backlight 8 is placed on the opposite side of the main liquid crystal display panel 6 to the display surface side, and a sub backlight 9 is placed on the opposite side of the sub liquid crystal display panel 7 to the display surface side.
The backlights 8 and 9 are of an edge light type. Although not shown in detail, reflectors 12 and 13 are bonded on the opposite sides of these backlights to the opposite sides to the liquid crystal display panels 6 and 7 to which optical waveguides 10 and 11 correspond, and a light source (not shown) such as a fluorescent tube or light-emitting diode is placed near one end face of each of the optical waveguides 10 and 11.
The light emitted from each light source is incident on one end face of each of the optical waveguides 10 and 11. The respective incident light beams are reflected by the reflectors 12 and 13 and two-dimensionally emerge from the opposite surfaces of the optical waveguides 10 and 11 to the liquid crystal display panels 6 and 7. These emerging light beams are incident on the liquid crystal display panels 6 and 7, and image light beams corresponding to the driving operations of the liquid crystal display panels 6 and 7 emerge from the display surface sides of the liquid crystal display panels 6 and 7.
In the conventional liquid crystal display apparatus, since the dedicated backlights 8 and 9 are respectively arranged for the liquid crystal display panels 6 and 7, a large number of components are required, and the thickness of the overall apparatus is large. This leads to an increase in the thickness of the display portion housing 2 of the cell phone.
It is an object of the present invention to provide a liquid crystal display apparatus which can decrease the number of components and the thickness of the overall apparatus.
According to an aspect of the present invention, there is provided a liquid crystal display apparatus comprising a first liquid crystal display panel, a second liquid crystal display panel smaller in area than the first liquid crystal display panel, a flat backlight which has an optical waveguide and a point light source placed near one side surface portion of the optical waveguide, and is placed between the first liquid crystal display panel and the second liquid crystal display panel, and one reflecting layer which is placed at least between the flat backlight and the second liquid crystal display panel.
According to this apparatus, since liquid crystal display panels are placed on the two surfaces of one optical waveguide, the number of components can be decreased, and the thickness of the overall apparatus can be reduced.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.